U.S. patent number 11,303,827 [Application Number 16/906,917] was granted by the patent office on 2022-04-12 for optical device for a thermal sensor and a hybrid thermal sensor.
This patent grant is currently assigned to Samsung Electronics Co., Ltd.. The grantee listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Radwanul Hasan Siddique, Yibing Michelle Wang.
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United States Patent |
11,303,827 |
Siddique , et al. |
April 12, 2022 |
Optical device for a thermal sensor and a hybrid thermal sensor
Abstract
An imaging device includes: a sensor to detect a first target
spectrum, the first target spectrum corresponding to a thermal
imaging region of an infrared (IR) spectrum; and an optical device
to transmit external light to the sensor, the optical device
including: a substrate; and a plurality of nanostructures on the
substrate, and to collimate at least the first target spectrum in
the external light on the sensor. The plurality of nanostructures
are spaced apart from each other, and at least one of the plurality
of nanostructures has a different geometric size from that of
another.
Inventors: |
Siddique; Radwanul Hasan
(Pasadena, CA), Wang; Yibing Michelle (Temple City, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si |
N/A |
KR |
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Assignee: |
Samsung Electronics Co., Ltd.
(Suwon-si, KR)
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Family
ID: |
1000006231563 |
Appl.
No.: |
16/906,917 |
Filed: |
June 19, 2020 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20210337140 A1 |
Oct 28, 2021 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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63016188 |
Apr 27, 2020 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01J
5/0803 (20130101); H04N 5/33 (20130101); G01J
2005/0077 (20130101) |
Current International
Class: |
H04N
5/33 (20060101); G01J 5/0803 (20220101); G01J
5/00 (20220101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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107315206 |
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Mar 2019 |
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CN |
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3428118 |
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Jan 2019 |
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EP |
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3499573 |
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Jun 2019 |
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EP |
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WO 2018/118984 |
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Jun 2018 |
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WO |
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2018/142339 |
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Aug 2018 |
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WO |
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WO 2019/148200 |
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Aug 2019 |
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WO |
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Other References
Adomanis, Bryan M., et al., "Sensitivities of Large-Aperture
Plasmonic Metasurface Flat Lenses in the Long-Wave Infrared,"
Proceedings of SPIE, vol. 10542, 2018, 10 pages. cited by applicant
.
Arbabi, Amir, et al, "Efficient dielectric metasurface collimating
lenses for mid-infrared quantum cascade lasers," OSA Publishing,
Optics Express, vol. 23, No. 26, 2015, 8 pages. cited by applicant
.
Li, Bo, et al., "Metalens-Based Miniaturized Optical Systems,"
Micromachines, vol. 10, 2019, 21 pages. cited by applicant .
Meem, Monjurul, et al., "Broadband lightweight flat lenses for
long-wave infrared imaging," PNAS, vol. 116, No. 43, Oct. 2019, 4
pages. cited by applicant .
Meem, Monjurul, et al., "Imaging from the Visible to the Longwave
Infrared wavelengths via an inverse-designed flat lens," arXiv:
Physics: Optics, Jan. 2020, 35 pages. cited by applicant.
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Primary Examiner: Haque; Md N
Attorney, Agent or Firm: Lewis Roca Rothgerber Christie
LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION(S)
This application claims priority to and the benefit of U.S.
Provisional Application No. 63/016,188, filed on Apr. 27, 2020,
entitled "FLAT OPTICS AND METALENSES FOR LWIR SENSOR, AND HYBRID
VISIBLE/LWIR SENSOR," the entire content of which is incorporated
by reference herein.
Claims
What is claimed is:
1. An imaging device comprising: a sensor configured to detect a
first target spectrum, the first target spectrum corresponding to a
thermal imaging region of an infrared (IR) spectrum; and an optical
device configured to transmit external light to the sensor, the
optical device comprising: a substrate; and a plurality of
nanostructures on the substrate, and configured to collimate at
least the first target spectrum in the external light on the
sensor, wherein the plurality of nanostructures are spaced apart
from each other, and at least one of the plurality of
nanostructures has a different geometric size from that of another,
and wherein the plurality of nanostructures comprise: a plurality
of first nanostructures comprising a material to transmit the first
target spectrum of the external light through, and configured to
collimate the first target spectrum of the external light on a
first sensing region of the sensor, the plurality of first
nanostructures comprising a first-first nanostructure, and a
first-second nanostructure adjacent to and spaced apart from the
first-first nanostructure; and at least one second nanostructure
comprising a material to transmit a second target spectrum of the
external light through, and configured to collimate the second
target spectrum of the external light on a second sensing region of
the sensor, the at least one second nanostructure being located
between and spaced apart from the first-first nanostructure and the
first-second nanostructure in a plan view, wherein the first target
spectrum is in a range between 8 .mu.m and 12 .mu.m, and the second
target spectrum is in a range between 0.4 .mu.m and 2.5 .mu.m,
wherein the substrate includes a first multisector region and a
second multisector region that do not overlap with each other in
the plan view, and wherein the first nanostructures are arranged at
the first multisector region, and the at least one second
nanostructure is arranged at the second multisector region.
2. The imaging device of claim 1, wherein the substrate includes
calcium fluoride, and the plurality of nanostructures includes a
high-index dielectric material.
3. The imaging device of claim 2, wherein the nanostructures have a
cylindrical or square shape.
4. The imaging device of claim 1, wherein the plurality of
nanostructures further comprise a plurality of second
nanostructures configured to collimate the second target spectrum
of the external light on the second sensing region of the sensor,
the plurality of second nanostructures comprising the at least one
second nanostructure.
5. The imaging device of claim 4, wherein the first nanostructures
and the second nanostructures are arranged at the same surface of
the substrate.
6. The imaging device of claim 4, wherein the first nanostructures
and the second nanostructures are arranged at opposite surfaces of
the substrate from each other.
7. The imaging device of claim 4, wherein at least one of the first
nanostructures has a larger geometric shape than those of the
second nanostructures.
8. The imaging device of claim 4 the second nanostructures are
arranged at the second multisector region.
9. An optical device comprising: a substrate; and a plurality of
nanostructures spaced apart on the substrate, and configured to
collimate at least a first target spectrum of external light on a
sensor, the first target spectrum corresponding to a thermal
imaging region of an infrared (IR) spectrum, wherein at least one
of the nanostructures have a different geometric size from that of
another, and wherein the plurality of nanostructures comprise: a
plurality of first nanostructures comprising a material to transmit
the first target spectrum of the external light through, and
configured to collimate the first target spectrum of the external
light on a first sensing region of the sensor, the plurality of
first nanostructures comprising a first-first nanostructure, and a
first-second nanostructure adjacent to and spaced apart from the
first-first nanostructure; and at least one second nanostructure
comprising a material to transmit a second target spectrum of the
external light through, and configured to collimate the second
target spectrum of the external light on a second sensing region of
the sensor, the at least one second nanostructure being located
between and spaced apart from the first-first nanostructure and the
first-second nanostructure in a plan view, wherein the first target
spectrum is in a range between 8 .mu.m and 12 .mu.m, and the second
target spectrum is in a range between 0.4 .mu.m and 2.5 .mu.m,
wherein the substrate includes a first multisector region and a
second multisector region that do not overlap with each other in
the plan view, and wherein the first nanostructures are arranged at
the first multisector region, and the at least one second
nanostructure is arranged at the second multisector region.
10. The optical device of claim 9, wherein the substrate includes
calcium fluoride, and the plurality of nanostructures include
silicon or amorphous silicon.
11. The optical device of claim 10, wherein the nanostructures have
a cylindrical shape or a square shape.
12. The optical device of claim 9, wherein the plurality of
nanostructures further comprise a plurality of second
nanostructures configured to collimate the second target spectrum
of the external light on the second sensing region of the sensor,
the plurality of second nanostructures comprising the at least one
second nanostructure.
13. The optical device of claim 12, wherein the first and second
nanostructures are arranged at one surface of the substrate, or are
arranged on opposite surfaces of the substrate from each other.
14. An optical device comprising: a substrate; a first
nanostructure on the substrate, and configured to collimate a first
target spectrum of external light on a first sensing region of a
sensor, the first target spectrum corresponding to a thermal
imaging region of an infrared (IR) spectrum; and a second
nanostructure on the substrate, and configured to collimate a
second target spectrum of the external light on a second sensing
region of the sensor, the second target spectrum being different
from the first target spectrum, wherein the first and second
nanostructures have different geometric sizes from each other,
wherein the first nanostructure comprises at least two adjacent
first nanostructures that are spaced apart from each other and
comprising a material to transmit the first target spectrum of the
external light through, and wherein the second nanostructure
comprises a material to transmit the second target spectrum of the
external light through, and is located between and spaced apart
from the at least two adjacent first nanostructures in a plan view,
wherein the first target spectrum is in a range between 8 .mu.m and
12 .mu.m, and the second target spectrum is in a range between 0.4
.mu.m and 2.5 .mu.m, wherein the substrate includes a first
multisector region and a second multisector region that do not
overlap with each other in the plan view, and wherein the first
nanostructure is arranged at the first multisector region, and the
second nanostructure is arranged at the second multisector
region.
15. The optical device of claim 14, wherein the first nanostructure
has a larger diameter or height than the second nanostructure.
Description
FIELD
Aspects of one or more example embodiments of the present
disclosure relate to optical devices, and more particularly, to
optical devices for a thermal sensor and a hybrid thermal
sensor.
BACKGROUND
An optical device, for example, such as a lens, may focus external
light (e.g., external light rays or external energy rays) on a
sensor such that an image (e.g., a thermal image or a visual image)
may be generated by the light detected by the sensor. For example,
the optical device may be made of a suitable transparent material
to transmit the external light through to a sensor, for example,
such as a thermal sensor or an image sensor. The sensor may have a
spectral sensitivity to a particular electromagnetic spectrum of
the external light, such that the sensor may detect the particular
spectrum in the external light transmitted thereto. For example, a
thermal image may be generated according to a thermal region of the
infrared spectrum of the external light detected by a thermal
sensor, and a visible image (e.g., an RGB image) may be generated
according to a visible spectrum of the external light detected by
an image sensor.
The transparent material of the optical device may be selected
according to the spectral sensitivity of the sensor in order to
transmit the particular spectrum of the external light through to
the sensor. For example, for thermal imaging, the transparent
material may be an infrared transparent material to allow the
thermal region of the infrared spectrum of the external light to be
transmitted through to a thermal sensor, and for visual imaging,
the transparent material may be a visible-light transparent
material to allow a suitable visible spectrum of the external light
to be transmitted through to an image sensor. However, infrared
transparent materials that are generally used in optical devices
and components for thermal sensors may be unsuitable for image
sensors, and visible-light transparent materials that are generally
used in optical devices and components for image sensors may be
unsuitable for thermal sensors.
The above information disclosed in this Background section is for
enhancement of understanding of the background of the present
disclosure, and therefore, it may contain information that does not
constitute prior art.
SUMMARY
One or more example embodiments of the present disclosure are
directed to an optical device, and an imaging device including the
optical device.
According to one or more example embodiments of the present
disclosure, an imaging device includes: a sensor configured to
detect a first target spectrum, the first target spectrum
corresponding to a thermal imaging region of an infrared (IR)
spectrum; and an optical device configured to transmit external
light to the sensor, the optical device comprising: a substrate;
and a plurality of nanostructures on the substrate, and configured
to collimate at least the first target spectrum in the external
light on the sensor. The plurality of nanostructures are spaced
apart from each other, and at least one of the plurality of
nanostructures has a different geometric size from that of
another.
In an example embodiment, the first target spectrum may be in a
range between 8 .mu.m and 12 .mu.m.
In an example embodiment, the substrate may include calcium
fluoride, and the plurality of nanostructures may include a
high-index dielectric material.
In an example embodiment, the nanostructures may have a cylindrical
or square shape.
In an example embodiment, the plurality of nanostructures may
include a first nanostructure configured to collimate the first
target spectrum of the external light on a first sensing region of
the sensor, and a second nanostructure configured to collimate a
second target spectrum of the external light on a second sensing
region of the sensor.
In an example embodiment, the first target spectrum may be in a
range between 8 .mu.m and 12 .mu.m, and the second target spectrum
may be in a range between 0.4 .mu.m and 2.5 .mu.m.
In an example embodiment, the first nanostructure and the second
nanostructure may be arranged at one surface of the substrate.
In an example embodiment, the first nanostructure and the second
nanostructure may be arranged at opposite surfaces of the substrate
from each other.
In an example embodiment, the first nanostructure may have a larger
geometric shape than that of the second nanostructure.
In an example embodiment, the substrate may include a first
multisector region and a second multisector region that do not
overlap with each other in a plan view, and the first nanostructure
may include a plurality of first nanostructures arranged at the
first multisector region, and the second nanostructure may include
a plurality of second nanostructures arranged at the second
multisector region.
According to one or more example embodiments of the present
disclosure, an optical device includes: a substrate; and a
plurality of nanostructures spaced apart on the substrate, and
configured to collimate at least a first target spectrum of
external light on a sensor, the first target spectrum corresponding
to a thermal imaging region of an infrared (IR) spectrum. At least
one of the nanostructures have a different geometric size from that
of another.
In an example embodiment, the first target spectrum may be in a
range between 8 .mu.m and 12 .mu.m.
In an example embodiment, the substrate may include calcium
fluoride, and the plurality of nanostructures may include silicon
or amorphous silicon.
In an example embodiment, the nanostructures may have a cylindrical
shape or a square shape.
In an example embodiment, the plurality of nanostructures may
include a first nanostructure configured to collimate the first
target spectrum of the external light on a first sensing region of
the sensor, and a second nanostructure configured to collimate a
second target spectrum of the external light on a second sensing
region of the sensor.
In an example embodiment, the first target spectrum may be in a
range between 8 .mu.m and 12 .mu.m, and the second target spectrum
of the external light may be in a range between 0.4 .mu.m and 2.5
.mu.m.
In an example embodiment, the first and second nanostructures may
be arranged at one surface of the substrate, or may be arranged on
opposite surfaces of the substrate from each other.
According to one or more example embodiments of the present
disclosure, an optical device includes: a substrate; a first
nanostructure on the substrate, and configured to collimate a first
target spectrum of external light on a first sensing region of a
sensor, the first target spectrum corresponding to a thermal
imaging region of an infrared (IR) spectrum; and a second
nanostructure on the substrate, and configured to collimate a
second target spectrum of the external light on a second sensing
region of the sensor, the second target spectrum being different
from the first target spectrum. The first and second nanostructures
have different geometric sizes from each other.
In an example embodiment, the first target spectrum may be in a
range between 8 .mu.m and 12 .mu.m, and the second target spectrum
may be in a range between 0.4 .mu.m and 2.5 .mu.m.
In an example embodiment, the first nanostructure may have a larger
diameter or height than the second nanostructure.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other aspects and features of the present disclosure
will become more apparent to those skilled in the art from the
following detailed description of the example embodiments with
reference to the accompanying drawings.
FIG. 1 illustrates a thermal imaging device according to one or
more example embodiments of the present disclosure.
FIGS. 2A-2C illustrate a hybrid thermal imaging device according to
one or more example embodiments of the present disclosure.
FIGS. 3A-3B illustrate a first target spectrum optical device
according to one or more example embodiments of the present
disclosure.
FIGS. 4A-4B illustrate a second target spectrum optical device
according to one or more example embodiments of the present
disclosure.
FIGS. 5A-5E illustrate a hybrid target spectrum optical device
according to one or more example embodiments of the present
disclosure.
FIG. 6 is a table showing a list of example suitable materials for
a substrate of the optical device according to one or more example
embodiments of the present disclosure.
FIG. 7 is a table showing a list of example suitable materials for
a nanostructure of the optical device according to one or more
example embodiments of the present disclosure.
FIGS. 8A-8B are graphs illustrating a relationship between the
transmission and phase of light and a diameter of a nanostructure
of the optical device according to one or more example embodiments
of the present disclosure.
FIGS. 9A-9B illustrate various examples of a hybrid thermal sensor
according to one or more example embodiments of the present
disclosure.
FIGS. 10A-10B illustrate a hybrid target spectrum optical device
according to one or more example embodiments of the present
disclosure.
DETAILED DESCRIPTION
Hereinafter, example embodiments will be described in more detail
with reference to the accompanying drawings, in which like
reference numbers refer to like elements throughout. The present
disclosure, however, may be embodied in various different forms,
and should not be construed as being limited to only the
illustrated embodiments herein. Rather, these embodiments are
provided as examples so that this disclosure will be thorough and
complete, and will fully convey the aspects and features of the
present disclosure to those skilled in the art. Accordingly,
processes, elements, and techniques that are not necessary to those
having ordinary skill in the art for a complete understanding of
the aspects and features of the present disclosure may not be
described. Unless otherwise noted, like reference numerals denote
like elements throughout the attached drawings and the written
description, and thus, descriptions thereof may not be
repeated.
Generally, infrared (IR) (e.g., IR light, IR energy, IR radiation,
and the like) is electromagnetic radiation having wavelengths in
the electromagnetic spectrum that are longer than those of visible
light, and thus, may be generally invisible to the naked human eye.
For example, the IR spectrum is a region of the electromagnetic
spectrum between the visible region and the microwave region, and
may extend from a nominal red edge of the visible region of about
0.7 micro-meters (.mu.m) to a nominal edge of the microwave region
of about 1 milli-meter (mm). For example, the IR spectrum includes
a near-infrared (NIR) band ranging from about 0.7 .mu.m to about
1.4 .mu.m, a short-wavelength infrared (SWIR) band ranging from
about 1.4 .mu.m to about 3 .mu.m, a mid-wavelength infrared (MWIR)
band ranging from about 3 .mu.m to about 8 .mu.m, a long-wavelength
infrared (LWIR) band ranging from about 8 .mu.m to about 15 .mu.m,
and a far infrared (FIR) band ranging from about 15 .mu.m to about
1 mm.
A thermal imaging device may generally utilize a thermal imaging
region of the IR spectrum to generate a corresponding thermal image
without active illumination (e.g., without active IR illumination).
For example, the thermal imaging region of the IR spectrum may
include the LWIR band (e.g., the LWIR spectrum) of the IR spectrum
corresponding to thermal emissions emitted by an object, such that
a corresponding thermal image of the object may be generated
without active illumination through detection of the LWIR band in
external light. In this case, a thermal sensor of the thermal
imaging device may be generally sensitive to the LWIR band of the
IR spectrum to detect the thermal emissions in the external light,
and may generate a heatmap corresponding to the detected LWIR band
in the external light, which may be used to generate the thermal
image. Thermal sensors may be important for use in various
applications ranging from, for example, security, medicine, and
autonomous driving to environmental and industrial monitoring.
An optical device of the thermal imaging device, for example, such
as a lens, may transmit the external light (e.g., including the
thermal emissions), and may focus (e.g., may bend) the external
light onto the thermal sensor. In this case, the optical device for
the thermal sensor may be made of a suitable IR-transparent
material to enable the thermal emissions in the external light to
be transmitted through, and may generally have a suitable phase
profile, or curvature and/or thickness to focus (e.g., to bend) the
transmitted external light onto the thermal sensor. For example, a
lens for a thermal sensor may be made of a suitable IR-transparent
material to transmit the LWIR band of the external light through,
and may generally have a suitable curvature and/or a suitable
thickness to focus the LWIR band in the external light on the
thermal sensor.
Optical devices for thermal sensors, for example, such as LWIR
sensors, may generally be expensive and/or bulky in size in order
to transmit and sufficiently focus the LWIR band of the external
light on the thermal sensor. For example, IR-transparent materials
that may be generally used for lenses and other optical components
in thermal sensors may include (e.g., may be made of), for example,
Germanium (Ge), Zinc Selenide (ZnSe), Zinc Sulfide (ZnS), Calcium
Fluoride (CaF2), Chalcogenide compounds, and/or the like, or
combinations thereof, which may be expensive and/or may cause the
lenses and other optical components to be bulky in size (e.g., due
to a curvature, a thickness, a weight, and/or the like) in order to
sufficiently focus the LWIR band in the external light. Reducing
the weight and/or thickness of optical devices for thermal sensors,
however, may be desired (e.g., may be crucial), for example, for
increasing the range of camera-carrying drones, reducing head and
neck injuries among camera-borne soldiers/users or alternative
reality (AR)/virtual reality (VR) applications, and/or the like.
Accordingly, an optical device for a thermal sensor having
decreased size and/or costs (e.g., manufacturing costs) may be
desired.
On the other hand, visible-light transparent materials, for
example, such as glass and/or the like, that may be generally used
for optical devices and components in image sensors, for example,
such as Complementary Metal-Oxide-Semiconductor (CMOS) image
sensors, may be unsuitable for thermal sensors. Visible-light
transparent materials may transmit visible light through
corresponding to the visible region of the electromagnetic spectrum
including a violet band (e.g., about 380-450 nanometers (nm)), a
blue band (e.g., about 450-485 nm), a cyan band (e.g., about
485-500 nm), a green band (e.g., about 500-565 nm), a yellow band
(e.g., about 565-590 nm), an orange band (e.g., about 590-625 nm),
and a red band (e.g., about 625-740 nm) of the visible spectrum.
Glass and other visible-light transparent materials that may be
generally used for optical devices and components in image sensors,
however, may absorb thermal radiation (e.g., thermal emissions),
and thus, may interfere with or may not be able to suitably
transmit the LWIR band of the external light through. Thus, optical
devices and components that may be generally used for image sensors
may be unsuitable for thermal sensors.
Further, due to optics limitations of their respective spectrums,
it may be difficult to integrate a thermal sensor with another kind
of sensor (e.g., an image sensor and/or the like) as a hybrid
thermal sensor (e.g., a multi-spectrum sensor implemented on a
single chip) capable of detecting both the LWIR band as well as
another target spectrum (e.g., the visible spectrum, the NIR band
of the IR spectrum, the SWIR band of the IR spectrum, and/or the
like) in the external light. For example, if the optical device of
the thermal sensor and the optical device of the image sensor are
integrated at the same or substantially the same optical path
length as each other, they may interfere with each other as they
may absorb the respective spectrums of light transmitted through.
However, combining visible imaging and thermal imaging into one
sensor (e.g., a hybrid sensor) may lower system costs and power
consumption, may enable better night vision applications, may
improve object recognition accuracy (e.g., especially live
objects), may enhance security and surveillance, and/or the like.
Accordingly, an optical device that may transmit and focus (e.g.,
collimate) the LWIR band of the IR spectrum and at least one other
target spectrum (e.g., the visible spectrum, the NIR band of the IR
spectrum, the SWIR band of the IR spectrum, and/or the like) of the
external light onto different sensing regimes (e.g., different
sensing regions) of a hybrid thermal sensor may be desired.
According to one or more example embodiments of the present
disclosure, an optical device, and an imaging device including the
optical device may be provided. In some embodiments, the optical
device may include a rigid or a flexible transparent substrate, and
a plurality of nanostructures disposed on the transparent
substrate. For example, in some embodiments, the optical device may
include (e.g., may be) a thin dielectric metasurface flat lens
(e.g., a metalens). The transparent substrate may include a
suitable transparent material to transmit one or more target
spectrums of external light through. The nanostructures may be
disposed on the substrate to have different geometric structures
and/or arrangements to focus the one or more target spectrums of
external light at the same or substantially the same focal distance
for each respective wavelength, or at different focal distances
from the same or substantially the same spatial location or from
different spatial locations depending on the desired application,
implementation, arrangement, structure, and/or the like of the
imaging device.
In some embodiments, the transparent material may be transparent to
at least the thermal region of the IR spectrum in external light.
For example, in some embodiments, the transparent material may
transmit a target range in the LWIR band of the IR spectrum. In
some embodiments, instead of focusing the external light according
to a curvature and/or a thickness of the substrate, the
nanostructures may be disposed on the substrate to focus the target
range of the LWIR band wavelengths in the external light on a
thermal sensor, for example, such as a LWIR sensor, such that a
thermal image may be generated according to the LWIR band
wavelengths in the external light detected by the thermal sensor.
Accordingly, in some embodiments, a size (e.g., a thickness) of the
substrate may be reduced, and thus, an optical device for a thermal
sensor having reduced cost, weight, and/or size may be
provided.
In some embodiments, the transparent material may further be
transparent to another target spectrum (e.g., the visible spectrum,
the NIR band of the IR spectrum, the SWIR band of the IR spectrum,
and/or the like) in the external light, in addition to the LWIR
band of the IR spectrum. For example, in some embodiments, the
transparent material may transmit the target range in the LWIR band
of the IR spectrum, as well as a target range in the visible
spectrum. In this case, in some embodiments, the nanostructures may
include a plurality of first nanostructures disposed on the
substrate to focus the target LWIR band wavelengths in the external
light to a thermal sensing region of a hybrid thermal sensor, and a
plurality of second nanostructures disposed on the substrate to
focus target wavelengths in the visible spectrum of the external
light on an image sensing region of the hybrid thermal sensor, for
example. A hybrid image (e.g., a thermal/visible image) may be
generated according to the respective wavelengths detected by the
hybrid thermal sensor. Accordingly, in some embodiments, an optical
device that may transmit and focus two or more different spectrums
of the external light onto different sensing regions for a hybrid
thermal sensor may be provided.
The above and other aspects and features of the present disclosure
will be described in more detail hereinafter with reference to the
figures.
FIG. 1 illustrates a thermal imaging device according to one or
more example embodiments of the present disclosure.
Referring to FIG. 1, the thermal imaging device 100 according to
one or more example embodiments of the present disclosure may be an
imaging device (e.g., a thermal camera, a night-vision camera,
and/or the like) that generates a thermal image by detecting a
target IR spectrum L1 in external light without active
illumination. For example, in some embodiments, the thermal imaging
device 100 may include one or more optical devices 102 and 104, and
one or more thermal sensors 106. The one or more optical devices
102 and 104 may transmit the external light therethrough to the one
or more thermal sensors 106, and the one or more thermal sensors
106 may have a suitable spectral sensitivity to the target IR
spectrum L1 in order to detect the target IR spectrum L1 in the
external light transmitted thereto. The one or more thermal sensors
106 may generate a heatmap according to the target IR spectrum L1
detected from the external light transmitted thereto, which may be
used to generate the thermal image. The thermal sensors 106 may be
cooled infrared photodetector based on narrow- or wide bandgap
semiconductors or uncooled photodetector based on pyroelectric and
ferroelectric materials or microbolometer technology.
In some embodiments, the target IR spectrum L1 may correspond to a
target range within the thermal imaging region of the IR spectrum.
For example, in some embodiments, the target IR spectrum L1 may
correspond to the LWIR band of the IR spectrum. In this case, the
target IR spectrum L1 may include an entire range of the LWIR band
of the IR spectrum, or may include a sub-range within the LWIR band
of the IR spectrum that is suitable for thermal imaging, for
example, such as a range between about 8 .mu.m to about 12 .mu.m
(e.g., a range between 8 .mu.m and 12 .mu.m), but the present
disclosure is not limited thereto. For example, in other
embodiments, the target IR spectrum L1 may include a range that
partially overlaps with a band in the IR spectrum adjacent to the
LWIR band, for example, such as a nominal edge of the MWIR band in
the IR spectrum.
In some embodiments, the one or more thermal sensors 106 may
include (e.g., may be) one or more high-resolution thermal sensors
capable of detecting the target IR spectrum L1 in the external
light transmitted thereto without active illumination, such that a
suitable thermal image (e.g., a high-resolution thermal image) may
be generated. For example, in some embodiments, the one or more
thermal sensors 106 may include (e.g., may be) a LWIR sensor array,
a LWIR resistive microbolometer, a LWIR capacitive microbolometer,
and/or the like to detect the target LWIR band in the external
light transmitted thereto, and to generate a suitable heat map
according to the detected target LWIR band in the external
light.
In some embodiments, the one or more optical devices 102 and 104
may include a first optical device 102 and a second optical device
104. The first optical device 102 may include (e.g., may be), for
example, a global lens of the thermal imaging device 100. The
second optical device 104 may include (e.g., may be), for example,
one or more micro-lenses of the thermal imaging device 100. In this
case, for example, the first optical device 102 may focus the
target IR spectrum L1 in the external light on the second optical
device 104, and the second optical device 104 may focus the target
IR spectrum L1 of the external light on the one or more thermal
sensors 106. For example, if the thermal sensor 106 includes the
LWIR sensor array, the second optical device 104 may include a
plurality of micro-lenses, each of the micro-lenses corresponding
to one or more sensor pixels of the LWIR sensor array to focus the
target IR spectrum L1 of the external light on the corresponding
one or more sensor pixels.
However, the present disclosure is not limited thereto, and in
other embodiments, the optical devices 102 and 104 may include more
or less optical devices than those shown in FIG. 1. For example, in
some embodiments, the first optical device 102 may include a
plurality of global lenses that are stacked on one another, or one
of the first optical device 102 or the second optical device 104
may be omitted depending on a structure or an application of the
thermal imaging device 100. For example, in some embodiments, if
the thermal imaging device 100 is implemented with an aperture, the
first optical device 102 (e.g., the global lens) may be omitted. In
another example, if the second optical device 104 is omitted, the
first optical device 102 may directly focus the target IR spectrum
L1 in the external light on the one or more thermal sensors
106.
In some embodiments, the first optical device 102 may include a
substrate 108 and a plurality of nanostructures 110 disposed on the
substrate 108. The substrate 108 may be a flexible substrate or a
rigid substrate, and may be formed of a suitable transparent
material to transmit at least the target IR spectrum L1 of the
external light through. For example, in some embodiments, the
transparent material may include calcium fluoride (CaF2). However,
the present disclosure is not limited thereto, and in other
embodiments, the transparent material may include any suitable
material that may transmit the target IR spectrum L1 through, for
example, such as polymers, silicon (Si), barium fluoride (BaF2),
potassium bromide (KBr), potassium chloride (KCl), sodium chloride
(NaCl), and/or the like, or a combination thereof.
In some embodiments, the substrate 108 may be flat or substantially
flat, but the present disclosure is not limited thereto, and the
substrate 108 may have a suitable curvature. For example, in some
embodiments, when the substrate 108 is a flexible substrate, the
substrate 108 may be flexed (e.g., bent, bowed, and/or the like) to
have a curvature. In some embodiments, the transparent material of
the substrate may be further transparent to one or more other
target spectrums (e.g., the visible spectrum, the NIR band of the
IR spectrum, the SWIR band of the IR spectrum, and/or the like),
such that the one or more other target spectrums may be suitably
transmitted through, but the present disclosure is not limited
thereto.
In some embodiments, the nanostructures 110 may be disposed on the
substrate 108, and may have various suitable materials, geometric
dimensions, and/or arrangements to focus (e.g., to collimate) the
relevant wavelengths in the external light propagating therethrough
to the one or more thermal sensors 106 via the second optical
device 104. For example, as the external light is propagating
through the nanostructures 110, the nanostructures 110 may change a
phase of the relevant wavelengths corresponding to the target IR
spectrum L1 in the external light to collimate the relevant
wavelengths of the external light on the one or more thermal
sensors 106 via the second optical device 104. However, the present
disclosure is not limited thereto, and if the second optical device
104 is omitted, the nanostructures 110 of the first optical device
102 may focus (e.g., may collimate) the relevant wavelengths of the
external light transmitted therethrough directly on the one or more
thermal sensors 106. In some embodiments, the nanostructures 110
may further filter (e.g., may block) unwanted spectrums of the
external light, for example, that may interfere with the target IR
spectrum L1.
In some embodiments, the nanostructures 110 may be formed of a
high-index dielectric material, for example, such as amorphous
silicon (a-Si), or any other suitable dielectric material, for
example, such as c-Si, p-Si, Ge, GaAs, ZnS, ZnSe, and/or the like,
or a combination thereof. In this case, in some embodiments, the
nanostructures 110 may be formed using a low cost, single-step
ultraviolet (UV) binary lithography process, but the present
disclosure is not limited thereto. For example, in other
embodiments, the nanostructures 110 may be formed of any suitable
material that may suitably transmit and collimate the target IR
spectrum L1 of the external light, for example, such as any
suitable one of the example materials or a suitable combination
thereof shown in FIG. 7, and/or the like. The nanostructures 110
will be described in more detail below with reference to FIGS. 3
through 8.
In some embodiments, the second optical device 104 may include a
substrate 112 and a plurality of nanostructures 114 arranged on the
substrate 112. The substrate 112 may be a flexible substrate or a
rigid substrate, and may be formed of a suitable transparent
material to transmit at least the target IR spectrum L1 from the
external light transmitted thereto by the first optical device 102.
For example, in some embodiments, the transparent material may
include calcium fluoride (CaF2). However, the present disclosure is
not limited thereto, and in other embodiments, the transparent
material may include any suitable material that may transmit the
target IR spectrum L1 therethrough, for example, such as barium
fluoride (BaF2), potassium bromide (KBr), potassium chloride (KCl),
sodium chloride (NaCl), and/or the like, or a combination thereof.
In some embodiments, the transparent material of the substrate 112
may be the same or substantially the same as the transparent
material of the substrate 108, but the present disclosure is not
limited thereto.
In some embodiments, the nanostructures 114 disposed on the
substrate 112 may further focus (e.g., may further collimate) the
target IR spectrum L1 of the external light propagating through on
the one or more thermal sensors 106. For example, in some
embodiments, the external light transmitted through the first
optical device 102 may diverge or may not converge as desired or
expected. In this case, the nanostructures 114 may further focus
(e.g., may further collimate) the diverged light onto the one or
more thermal sensors 106, for example, to one or more respective
sensor pixels associated with the second optical device 104 in the
case of the LWIR sensor array. In some embodiments, the
nanostructures 114 may further filter (e.g., may block) unwanted
spectrums of the external light propagating therethrough, for
example, that may interfere with the target IR spectrum L1 of the
external light.
For example, in some embodiments, the nanostructures 114 may be
disposed on the substrate 112, and may have various suitable
materials, geometric dimensions, and/or arrangements, such that the
nanostructures 114 may suitably change a phase of the relevant
wavelengths of the external light propagating therethrough to
collimate the relevant wavelengths of the external light on the one
or more thermal sensors 106 (e.g., to one or more respective sensor
pixels thereof). In some embodiments, the nanostructures 114 may be
formed of a high-index dielectric material, for example, such as
amorphous silicon (a-Si), or any other suitable dielectric
material, for example, such as c-Si, p-Si, Ge, GaAs, ZnS, ZnSe,
and/or the like, or a combination thereof. In this case, in some
embodiments, the nanostructures 114 may be formed using a low cost,
single-step ultraviolet (UV) binary lithography process, but the
present disclosure is not limited thereto. For example, in other
embodiments, the nanostructures 114 may be formed of any suitable
material that may suitably transmit and collimate the target IR
spectrum L1 of the external light propagating thereto, for example,
such as any one of the example materials or a suitable combination
thereof shown in FIG. 7, and/or the like. In some embodiments, the
nanostructures 114 may be formed of the same or substantially the
same material as that of the nanostructures 110, but the present
disclosure is not limited thereto. The nanostructures 114 will be
described in more detail below with reference to FIGS. 3 through
8.
According to one or more example embodiments of the present
disclosure, the optical devices 102 and 104 for the thermal imaging
device 100 may have a reduced size and/or costs when compared to a
comparative lens that may be generally used for thermal imaging
devices. For example, because the optical devices 102 and 104 may
include the nanostructures 110 and 114 to transmit and collimate
the target IR spectrum L1 of the external light on the one or more
thermal sensors 106, a thickness, a curvature, a weight, and/or the
like of the optical devices 102 and 104 may be reduced, and/or
costs for manufacturing the optical devices 102 and 104 may be
reduced.
FIGS. 2A through 2C illustrate various examples of a hybrid thermal
imaging device according to one or more example embodiments of the
present disclosure. FIGS. 9A and 9B illustrate various examples of
a hybrid thermal sensor according to one or more example
embodiments of the present disclosure.
Referring to FIGS. 2A through 2C, the hybrid thermal imaging device
200 according to one or more example embodiments of the present
disclosure may be an imaging device (e.g., a camera) that includes
a hybrid thermal sensor (e.g., a thermal sensor combined with
another kind of sensor) 206 to generate a combined hybrid thermal
image. A combined hybrid thermal image as used in this
specification may be an image generated according to a combination
of a thermal image with another kind of image, for example, such as
a visible image (e.g., an RGB image). In other words, the combined
hybrid thermal image may be an image that is generated by combining
thermal information with another kind of spectral information
detected in the external light by the hybrid thermal sensor 206,
for example, such as visible light.
Generally, in order to combine a thermal image with a visible image
(e.g., an RGB image), due to the optics limitations of their
respective spectrums as discussed above, a thermal camera including
a thermal sensor may be used to generate the thermal image, and a
separate image camera (e.g., a separate CMOS camera) including an
image sensor (e.g., a CMOS sensor) may be used to generate the
visible image. In this case, the thermal image generated by the
thermal camera may be combined with the visible image generated by
the separate image camera using complex image processing
techniques, for example, to align different views (e.g., different
field-of-views) of the thermal camera and the separate image
camera, and/or to merge their respective views with each other.
However, in this case, system costs and/or power consumption may be
increased, and latency may be introduced.
According to one or more example embodiments of the present
disclosure, the hybrid thermal imaging device 200 may include the
hybrid thermal sensor 206 and one or more optical devices 202, 104,
and 204. The hybrid thermal sensor 206 may detect the target IR
spectrum L1 in external light without active illumination, as well
as another target spectrum L2 (e.g., the visible spectrum, the NIR
band of the IR spectrum, the SWIR band of the IR spectrum, and/or
the like) in the external light that is different from the target
IR spectrum L1, such that a combined hybrid thermal image may be
generated according to the different spectrums detected by the
hybrid thermal sensor 206. The one or more optical devices 202,
104, and 204 may transmit both the target IR spectrum L1 and the
other target spectrum L2 in the external light, and may focus
(e.g., may collimate) the target IR spectrum L1 and the other
target spectrum L2 to respective sensing regions of the hybrid
thermal sensor 206. Accordingly, in some embodiments, system costs
and/or power consumption may be reduced, and latency may be
reduced.
In more detail, in some embodiments, the hybrid thermal sensor 206
may include a first sensing region 216 and a second sensing region
218. The first sensing region 216 may have a suitable spectral
sensitivity to the target IR spectrum L1, and the second sensing
region 218 may have a suitable spectral sensitivity to the other
target spectrum L2. For example, the target IR spectrum L1 may
correspond to a target range corresponding to the LWIR band of the
IR spectrum as discussed above, and the other spectrum L2 may
correspond to a target range outside of the LWIR band, for example,
such as a target range in the visible spectrum, the NIR band of the
IR spectrum, the SWIR band of the IR spectrum, and/or the like. For
a non-limiting example, in some embodiments, the target IR spectrum
L1 may include a range between about 8 .mu.m to about 12 .mu.m
(e.g., a range between 8 .mu.m and 12 .mu.m), and the other target
spectrum L2 may include a range between about 0.4 .mu.m to about
2.5 .mu.m (e.g., a range between 0.4 .mu.m and 2.5 .mu.m). For
convenience, the other target spectrum L2 may be described
hereinafter in the context of the visible spectrum, but the present
disclosure is not limited thereto.
In some embodiments, the first sensing region 216 and the second
sensing region 218 may be implemented as a sensor array including a
plurality of first sensor pixels and a plurality of second sensor
pixels. For example, in some embodiments, the first sensing region
216 may include the first sensor pixels corresponding to LWIR
sensor pixels to detect the target IR spectrum L1, and the second
sensing region 216 may include the second sensor pixels
corresponding to image sensor pixels (e.g., CMOS sensor pixels) to
detect the other target spectrum L2. In this case, the first sensor
pixels of the first sensing region 216 and the second sensor pixels
of the second sensing region 218 may have any suitable arrangement
with respect to each other, for example, such as a pentile
arrangement, a stripe arrangement, a side-by-side arrangement, a
stacked arrangement, and/or the like.
As a non-limiting example, as shown in FIGS. 2A and 9A, in some
embodiments, the hybrid thermal sensor 206 may be implemented as an
interleaved sensor pixel array 902 including a plurality of the
first sensing regions 216 implemented as a plurality of the first
sensor pixels, and a plurality of the second sensing regions 218
implemented as a plurality of the second sensor pixels. In this
case, the first sensor pixels and the second sensor pixels of the
interleaved sensor pixel array 902 may be arranged to have any
suitable interleaved arrangement with respect to each other. As
another non-limiting example, as shown in FIGS. 2C and 9B, in some
embodiments, the hybrid thermal sensor 206 may be implemented as a
multi-sectoral sensor pixel array including a first pixel array 904
and a second pixel array 906. The first pixel array 904 may include
the plurality of first sensing regions 216 implemented as a
plurality of the first sensor pixels, and the second pixel array
906 may include the plurality of second sensing regions 218
implemented as a plurality of the second sensor pixels.
In some embodiments, as shown in FIGS. 2A and 2C, the first sensing
region 216 and the second sensing region 218 may be disposed at a
same plane as each other (e.g., may be disposed at a same layer as
each other), and/or as shown in FIG. 2B, the first sensing region
216 and the second sensing region 218 may be stacked on one another
(e.g., may be disposed at different layers from each other).
Accordingly, focal lengths of the first and second sensing regions
216 and 218 of the hybrid thermal sensor 206 may be the same or
substantially the same as each other, or may be different from each
other.
In some embodiments, the one or more optical devices 202, 104, and
204 may include a first optical device 202, a second optical device
104, and a third optical device 204. The first optical device 202
may include (e.g., may be), for example, a global lens of the
hybrid thermal imaging device 200. Each of the second and third
optical devices 104 and 204 may include (e.g., may be), for
example, one or more micro-lenses of the hybrid thermal imaging
device 200. For example, the second optical device 104 may
correspond to the first sensing region 216 of the hybrid thermal
sensor 206, and may include a plurality of micro-lenses, each of
the micro-lenses corresponding to one or more of the first sensor
pixels of the first sensing region 216. The third optical device
204 may correspond to the second sensing region 218 of the hybrid
thermal sensor 206, and may include a plurality of micro-lenses,
each of the micro-lenses corresponding to one or more of the second
sensor pixels of the second sensing region 218. For example, an
arrangement of the micro-lenses of the second optical device 104
and the third optical device 204 may correspond to (e.g., may
follow) an arrangement of the sensor pixel array of the hybrid
thermal sensor 206 (e.g., interleaved, side-by-side, stacked,
and/or the like).
The first optical device 202 may focus the target IR spectrum L1
and the other target spectrum L2 of the external light on the first
and second regions 216 and 218 of the hybrid thermal sensor 206 via
the second and third optical devices 104 and 204, and the second
and third optical devices 104 and 204 may further focus the target
IR spectrum L1 and the other target spectrum L2 on the first and
second sensing regions 216 and 218 of the hybrid thermal sensor
206, respectively. For example, in some embodiments, the second
optical device 104 may further focus the target IR spectrum L1 of
the light transmitted through the first optical device 202 on the
first sensing region 216 of the hybrid thermal sensor 206, and the
third optical device 204 may further focus the other target
spectrum L2 of the light transmitted through the first optical
device 202 on the second sensing region 218 of the hybrid thermal
sensor 206.
However, the present disclosure is not limited thereto, and in
other embodiments, the optical devices 202, 104, and 204 may
include more or less optical devices than those shown in FIGS. 2A
and 2B. For example, in some embodiments, the first optical device
202 may include a plurality of global lenses that are stacked on
one another, or one or more of the first optical device 202, the
second optical device 104, or the third optical device 204 may be
omitted depending on a structure or an application of the hybrid
thermal imaging device 200. For example, in some embodiments, if
the hybrid thermal imaging device 200 is implemented with an
aperture, the first optical device 202 (e.g., the global lens) may
be omitted. In another example, if the second optical device 104
and/or the third optical device 204 is omitted, the first optical
device 202 may directly focus the target IR spectrum L1 of the
external light on the first sensing region 216, and/or may directly
focus the other target spectrum L2 of the external light on the
second sensing region 218.
In some embodiments, the first optical device 202 may include a
substrate 208 and a plurality of nanostructures 210 disposed on the
substrate 208. The substrate 208 may be a flexible substrate or a
rigid substrate, and may be formed of a suitable transparent
material to suitably transmit at least both the target IR spectrum
L1 and the other target spectrum L2 in the external light. For
example, in some embodiments, the transparent material may include
calcium fluoride (CaF2). However, the present disclosure is not
limited thereto, and in other embodiments, the transparent material
may include any suitable material that may suitably transmit at
least both the target IR spectrum L1 and the other target spectrum
L2 through, for example, such as polymers, silicon (Si), barium
fluoride (BaF2), potassium bromide (KBr), potassium chloride (KCl),
sodium chloride (NaCl), and/or the like, or a combination thereof.
In some embodiments, the substrate 208 may be flat or substantially
flat, but the present disclosure is not limited thereto, and the
substrate 208 may have a suitable curvature. For example, in some
embodiments, when the substrate 208 is a flexible substrate, the
substrate 208 may be flexed (e.g., bent, bowed, and/or the like) to
have a curvature.
In some embodiments, the nanostructures 210 disposed on the
substrate 208 may focus (e.g., may collimate) the target IR
spectrum L1 and the other target spectrum L2 of the external light
propagating through on the first and second sensing regions 216 and
218 of the hybrid thermal sensor 206 via the second and third
optical devices 104 and 204, respectively. However, the present
disclosure is not limited thereto, and if the second and third
optical devices 104 and 204 are omitted, the nanostructures 210 of
the first optical device 202 may focus (e.g., may collimate) the
target IR spectrum L1 and the other spectrum L2 of the external
light propagating through directly to respective sensing regions
216 and 218 of the hybrid thermal sensor 206.
For example, in some embodiments, the nanostructures 210 may be
disposed on the substrate 208 to have various suitable geometric
dimensions and/or arrangements, such that the nanostructures 210
may change a phase of the target IR spectrum L1 of the external
light propagating through to sufficiently collimate the target IR
spectrum L1 of the external light on the second optical device 104
(or on the first sensing region 216 directly), and may change a
phase of the other target spectrum L2 of the external light
propagating through to sufficiently collimate the other target
spectrum L2 on the third optical device 204 (or on the second
sensing region 218 directly). For example, in some embodiments, the
nanostructures 210 may include a plurality of first nanostructures
and a plurality of second nanostructures (e.g., see FIGS. 5A-5D and
10A-10B). The plurality of first nanostructures may focus (e.g.,
may collimate) the target IR spectrum L1 of the external light
propagating through on the second optical device 104 (or on the
first sensing region 216 directly), and the second nanostructures
may focus (e.g., may collimate) the other target spectrum L2 of the
external light propagating through on the third optical device 204
(or on the second sensing region 218 directly).
In various embodiments, the nanostructures 210 may focus the
external light at the same or substantially the same focal distance
for each wavelength of the target spectrums L1 and L2, or at
different focal distances at the same or substantially the same
spatial location or at different spatial locations. For example,
when the first and second sensing regions 216 and 218 (or the
second and third optical devices 104 and 204) of the hybrid thermal
sensor 206 are disposed at the same or substantially the same focal
length from the first optical device 202 as each other, for
example, as shown in FIGS. 2A and 2C, the first and second
nanostructures of the nanostructures 210 may focus the wavelengths
of their respective target spectrum L1 and L2 at the same or
substantially the same focal distance as each other. In another
example, when the first and second sensing regions 216 and 218 (or
the second and third optical devices 104 and 204) of the hybrid
thermal sensor 206 are disposed at different focal lengths from the
first optical device 202 as each other, for example, as shown in
FIG. 2B, the first and second nanostructures of the nanostructures
210 may focus the wavelengths of their respective target spectrum
L1 and L2 at different focal lengths from each other.
In some embodiments, the nanostructures 210 may be formed of a
high-index dielectric material, for example, such as amorphous
silicon (a-Si), or any other suitable dielectric material, for
example, such as c-Si, p-Si, Ge, GaAs, ZnS, ZnSe, Si.sub.3N.sub.4,
TiO.sub.2, HfO.sub.2, and/or the like, or a combination thereof. In
this case, in some embodiments, the nanostructures 210 may be
formed using a low cost, single-step ultraviolet (UV, deep UV)
binary lithography process, but the present disclosure is not
limited thereto. For example, in other embodiments, the
nanostructures 210 may be formed of any suitable material to
suitably transmit and collimate the target spectrums L1 and L2 of
the external light, for example, such as any suitable one of the
example materials or a suitable combination thereof shown in FIG.
7, and/or the like. In some embodiments, the first and second
nanostructures of the nanostructures 210 may include the same or
substantially the same material as each other, or may include
different materials from each other. The nanostructures 210 will be
described in more detail below with reference to FIGS. 3 through 8
and 10.
In some embodiments, the second optical device 104 may include a
substrate 112 and a plurality of nanostructures 114 arranged on the
substrate 112. The substrate 112 may be a flexible substrate or a
rigid substrate, and may be formed of a suitable transparent
material to transmit at least the target IR spectrum L1 from the
external light transmitted thereto by the first optical device 202.
For example, in some embodiments, the transparent material may
include calcium fluoride (CaF2), polymer, SiO.sub.2, or silicon
(Si). However, the present disclosure is not limited thereto, and
in other embodiments, the transparent material may include any
suitable material that may sufficiently transmit the target IR
spectrum L1, for example, such as polymers, silicon (Si, a-Si,
p-Si), barium fluoride (BaF2), potassium bromide (KBr), potassium
chloride (KCl), sodium chloride (NaCl), and/or the like, or a
combination thereof. In some embodiments, the transparent material
of the substrate 112 may be the same or substantially the same as
the transparent material of the substrate 208, but the present
disclosure is not limited thereto.
In some embodiments, the nanostructures 114 disposed on the
substrate 112 may further focus (e.g., may further collimate) the
target IR spectrum L1 of the external light propagating
therethrough to the first sensing region 216 of the hybrid thermal
sensor 206. For example, in some embodiments, the external light
transmitted through the first optical device 202 may diverge or may
not converge as desired or expected. In this case, the
nanostructures 114 may further focus (e.g., may further collimate)
the diverged light on the first sensing region 216 of the hybrid
thermal sensor 206, for example, on one or more respective first
sensor pixels associated with the second optical device 104. In
some embodiments, the nanostructures 114 may further filter (e.g.,
may block) unwanted spectrums of the external light propagating
therethrough, for example, that may interfere with the target IR
spectrum L1 of the external light.
For example, in some embodiments, the nanostructures 114 may be
disposed on the substrate 112 to have various suitable materials,
geometric dimensions, and/or arrangements to sufficiently transmit
and collimate the target IR spectrum L1 of the external light on
the first sensing region 216 of the hybrid thermal sensor 206
(e.g., on one or more respective first sensor pixels thereof). In
some embodiments, the nanostructures 114 may be formed of a
high-index dielectric material, for example, such as amorphous
silicon (a-Si), or any other suitable dielectric material, for
example, such as silicon (c-Si, p-Si), barium fluoride (BaF2),
potassium bromide (KBr), potassium chloride (KCl), sodium chloride
(NaCl), and/or the like, or a combination thereof. In this case, in
some embodiments, the nanostructures 114 may be formed using a low
cost, single-step ultraviolet (UV, deep UV) binary lithography
process, but the present disclosure is not limited thereto. For
example, in other embodiments, the nanostructures 114 may be formed
of any suitable material to suitably collimate the target IR
spectrum L1 of the external light propagating therethrough, for
example, such as any suitable one of the example materials or a
suitable combination thereof shown in FIG. 7, and/or the like. The
nanostructures 114 will be described in more detail below with
reference to FIGS. 3 through 8.
In some embodiments, the third optical device 204 may include a
substrate 212 and a plurality of nanostructures 214 arranged on the
substrate 212. The substrate 212 may be a flexible substrate or a
rigid substrate, and may be formed of a suitable transparent
material to transmit at least the other target spectrum L2 through
from the external light transmitted thereto by the first optical
device 202. For example, in some embodiments, the transparent
material may include calcium fluoride (CaF2). However, the present
disclosure is not limited thereto, and in other embodiments, the
transparent material may include any suitable material that may
transmit the other target spectrum L2 therethrough, for example,
such as polymers, Silicon (a-Si, c-Si, p-Si), SiO.sub.2, barium
fluoride (BaF2), potassium bromide (KBr), potassium chloride (KCl),
sodium chloride (NaCl), and/or the like, or a combination thereof.
In some embodiments, the transparent material of the substrate 212
may be the same or substantially the same as the transparent
material of the substrate 112, or may be different from that of the
substrate 112.
In some embodiments, the nanostructures 214 disposed on the
substrate 212 may further focus (e.g., may further collimate) the
other target spectrum L2 of the external light propagating
therethrough on the second sensing region 218 of the hybrid thermal
sensor 206. For example, in some embodiments, the external light
transmitted through the first optical device 202 may diverge or may
not converge as desired or expected. In this case, the
nanostructures 214 may further focus (e.g., may further collimate)
the diverged light on the second sensing region 218 of the hybrid
thermal sensor 206, for example, on one or more respective second
sensor pixels associated with the third optical device 204. In some
embodiments, the nanostructures 214 may further filter (e.g., may
block) unwanted spectrums of the external light propagating
therethrough, for example, that may interfere with the other target
spectrum L2 of the external light.
For example, in some embodiments, the nanostructures 214 may be
disposed on the substrate 212 to have various suitable materials,
geometric dimensions, and/or arrangements to transmit and collimate
the other target spectrum L2 of the external light towards the
second sensing region 218 of the hybrid thermal sensor 206 (e.g.,
to one or more respective second sensor pixels thereof). In some
embodiments, the nanostructures 214 may be formed of a high-index
dielectric material, for example, such as amorphous silicon (a-Si)
or any other suitable dielectric material, for example, such as
silicon nitride (Si.sub.3N.sub.4), titania (TiO.sub.2), silicon
(c-Si, p-Si), and/or the like, or a combination thereof. In this
case, in some embodiments, the nanostructures 214 may be formed
using a low cost, single-step ultraviolet (UV, deep UV) binary
lithography process, but the present disclosure is not limited
thereto. For example, in other embodiments, the nanostructures 214
may be formed of any suitable material that may suitably collimate
the other target spectrum L2 of the external light propagating
through, for example, such as any suitable one of the example
materials or a suitable combination thereof shown in FIG. 7, and/or
the like. In some embodiments, the nanostructures 214 may include
the same or substantially the same material as that of the
nanostructures 114, but the present disclosure is not limited
thereto, and in other embodiments, the nanostructures 214 may
include a different material from that of the nanostructures 114.
The nanostructures 214 will be described in more detail below with
reference to FIGS. 3 through 8 and 10.
According to one or more example embodiments of the present
disclosure, the optical devices 202, 104, and 204 for the hybrid
thermal imaging device 200 may transmit and focus at least two
different spectrums of external light to different sensing regions
216 and 218 of the hybrid thermal sensor 206 located at the same or
different focal lengths from each other to detect different kinds
of spectral information (e.g., different spectrums) from the
external light. Thus, a hybrid thermal image may be generated from
the different kinds of spectral information detected by the hybrid
thermal sensor 206 from the external light at the same or
substantially the same view-point from the same imaging device,
rather than combining a thermal image captured from a thermal
camera and separate image captured from a separate image camera.
Accordingly, system costs and/or power consumption may be reduced,
and latency may be reduced.
FIGS. 3A and 3B illustrate a first target spectrum optical device
according to one or more example embodiments of the present
disclosure. For example, FIG. 3A shows a plan view, and FIG. 3B
shows a cross-sectional view of the first target spectrum optical
device 300. FIGS. 4A and 4B illustrate a second target spectrum
optical device according to one or more example embodiments of the
present disclosure. For example, FIG. 4A shows a plan view, and
FIG. 4B shows a cross-sectional view of the second target spectrum
optical device 400. FIGS. 5A through 5E illustrate a hybrid target
spectrum optical device according to one or more example
embodiments of the present disclosure. For example, FIG. 5A shows a
plan view, and FIGS. 5B through 5D show various example embodiments
of a cross-sectional view of the hybrid target spectrum optical
device 500. FIG. 5E shows an example embodiment of a perspective
view of the hybrid target spectrum optical device 500.
According to one or more example embodiments of the present
disclosure, the first target spectrum optical device 300 may be an
optical device for a thermal sensor, for example, such as a global
lens or a micro-lens of a thermal imaging device, that may transmit
and focus (e.g., collimate) the target IR spectrum L1 of the
external light to the thermal sensor or a thermal sensing region of
a hybrid thermal sensor. The second target spectrum optical device
400 may be an optical device for an image sensor, for example, such
as a global lens for an image sensor or a micro-lens corresponding
to a visible-light sensing region of a hybrid thermal sensor, that
may transmit and focus (e.g., collimate) the other target spectrum
L2 of the external light to the image sensor or the visible-light
sensing region of the hybrid thermal sensor. The hybrid target
spectrum optical device 500 may be an optical device for a hybrid
thermal sensor, for example, such as a global lens of a hybrid
thermal imaging device or a micro-lens for one or more sensing
regions of the hybrid thermal sensor, that may transmit and focus
(e.g., collimate) at least both the target IR spectrum L1 and the
other target spectrum L2 of external light to respective sensing
regions of the hybrid thermal sensor (or to respective micro-lenses
of the hybrid thermal sensor).
For example, in some embodiments, the first optical device 102
shown in FIG. 1 and/or the second optical device 104 shown in FIGS.
1, 2A, and 2B may have the same or substantially the same structure
as that of the first target spectrum optical device 300 shown in
FIGS. 3A and 3B, the third optical device 204 shown in FIGS. 2A and
2B may have the same or substantially the same structure as that of
the second target spectrum optical device 400 shown in FIGS. 4A and
4B, and the first optical device 202 shown in FIGS. 2A and 2B may
have the same or substantially the same structure as that of any
suitable one of the hybrid target spectrum optical device 500 shown
in FIGS. 5A through 5E. Accordingly, redundant description thereof
may be simplified or may not be repeated. However, the present
disclosure is not limited thereto, and any of the first, second,
and third optical devices 102, 202, 104, and 204 may have the same
or substantially the same structure as any suitable one of the
optical devices 300, 400, and 500 shown in FIGS. 3A through 5E
depending on the desired application, implementation, arrangement,
structure, and/or the like of the imaging device.
According to one or more example embodiments of the present
disclosure, each of the first target spectrum optical device 300,
the second target spectrum optical device 400, and the hybrid
target spectrum optical device 500 may include a transparent
substrate 302, 402, or 502. Each of the substrates 302, 402, and
502 may be a flexible substrate or a rigid substrate, and may be
flat or substantially flat. However, the present disclosure is not
limited thereto, and in some embodiments, any of the substrates
302, 402, and/or 502 may have a suitable curvature depending on the
characteristics, material, application, and/or structure thereof.
While FIGS. 3A, 4A, and 5A illustrate that the substrates 302, 402,
and 502 may have a circular shape in a plan view (e.g., a view from
the z-axis direction), the present disclosure is not limited
thereto, and each of the substrates 302, 402, and 502 may have any
suitable shape in the plan view, for example, such as an elliptical
shape, a triangular shape, a quadrilateral shape, a pentagon shape,
a hexagon shape, an oblong shape, and/or the like.
The substrates 302, 402, and 502 may each include (e.g., may each
be made of) a suitable transparent material to transmit at least
their respective target spectrums L1 and L2 of external light. For
example, the substrate 302 of the first target spectrum optical
device 300 may include a suitable IR transparent material to allow
at least the target IR spectrum L1 (e.g., a range between about 8
.mu.m to about 12 .mu.m) to be transmitted through, the substrate
402 of the second target spectrum optical device 300 may include a
suitable visible-light transparent material to allow at least the
other target spectrum L2 (e.g., any suitable range between about
0.4 .mu.m and about 2.5 .mu.m) to be transmitted through, and the
substrate 502 of the hybrid target spectrum optical device 500 may
include a suitable IR transparent material to allow at least both
the target IR spectrum L1 and the other target spectrum L2 to be
transmitted through.
In various embodiments, the substrates 302, 402, and 502 may
include the same or substantially the same material as each other,
or at least one of the substrates 302, 402, and 502 may include one
or more different materials from those of the others. For example,
in some embodiments, the substrates 302, 402, and 502 may each
include (e.g., may each be made of) calcium fluoride (CaF2).
However, the present disclosure is not limited thereto, and in
other embodiments, the substrates 302, 402, and 502 may each
include any suitable material that may transmit their respective
target spectrums L1 and L2 through, for example, such as polymers,
Si (a-Si, c-SI, p-Si), barium fluoride (BaF2), potassium bromide
(KBr), potassium chloride (KCl), sodium chloride (NaCl), and/or the
like, or a combination thereof.
The first target spectrum optical device 300 may include a
plurality of first nanostructures 304 that are disposed on the
substrate 302 to be spaced apart from each other, and the second
target spectrum optical device 400 may include the plurality of
second nanostructures 404 that are disposed on the substrate 402 to
be spaced apart from each other. The hybrid target spectrum optical
device 500 may include both the plurality of first nanostructures
304 and the plurality of second nanostructures 404 that are
disposed on the substrate 502 to be spaced apart from each other.
For example, each of the substrates 302, 402, and 502 may have an
external surface that faces the external light (e.g., L1 and L2),
and an internal surface that faces a sensor (e.g., an image sensor,
a thermal sensor, a hybrid thermal sensor, and/or the like) of the
imaging device. In some embodiments, respective ones of the first
and second nanostructures 304 and 404 may be disposed on the
internal surface of the substrates 302, 402, and 502 to be spaced
apart from each other, and may extend towards the sensor in a
thickness direction (e.g., a z-axis direction).
In other embodiments, as shown in FIG. 5E, the substrate 502 may
include a first surface and a second surface. The first and second
surfaces may be opposite surfaces (e.g., in the z-axis direction),
such that the first and second surfaces may face away from each
other. In some embodiments, the plurality of first nanostructures
304 may be disposed on the first surface of the substrate 502 to be
spaced apart from each other, and the plurality of second
nanostructures 404 may be disposed on the second surface of the
substrate 502 to be spaced apart from each other. In some
embodiments, the first nanostructures 304 may not overlap with the
second nanostructures 404 in the thickness direction (e.g., in the
z-axis direction).
For example, in some embodiments, as shown in FIGS. 3A and 3B, the
first target spectrum optical device 300 may include the first
nanostructures 304 arranged on the internal surface of the
substrate 302 along a first direction (e.g., an x-axis direction)
and a second direction (e.g., a y-axis direction) in which the
substrate 302 extends. The first nanostructures 304 may be spaced
apart from each other, and may each extend in the thickness
direction (e.g., the z-axis direction). The first nanostructures
304 may have various suitable geometric shapes, sizes, and/or
arrangements to sufficiently focus (e.g., to sufficiently
collimate) the target IR spectrum L1 propagating therethrough on a
desired spatial location (e.g., on a desired thermal sensor or a
desired sensing region of the thermal sensor). While FIG. 3B
illustrates that the first nanostructures 304 of the first target
spectrum optical device 300 has a single layer structure, the
present disclosure is not limited thereto, and in some embodiments,
the first nanostructures 304 of the first target spectrum optical
device 300 may have a multi-layered structure. In this case, for
example, in some embodiments, the first target spectrum optical
device 300 may have multiple layers of the first nanostructures
304.
In another example, in some embodiments, as shown in FIGS. 4A and
4B, the second target spectrum optical device 400 may include the
second nanostructures 404 arranged on the internal surface of the
substrate 402 along a first direction (e.g., an x-axis direction)
and a second direction (e.g., a y-axis direction) in which the
substrate 402 extends. The second nanostructures 404 may be spaced
apart from each other, and may each extend in the thickness
direction (e.g., the z-axis direction). The second nanostructures
404 may have various suitable geometric shapes, sizes, and/or
arrangements to sufficiently focus (e.g., to sufficiently
collimate) the other target spectrum L2 propagating therethrough on
a desired spatial location (e.g., on a desired sensor or a desired
sensing region of the sensor). While FIG. 4B illustrates that the
second nanostructures 404 of the second target spectrum optical
device 400 has a single layer structure, the present disclosure is
not limited thereto, and in some embodiments, the second
nanostructures 404 of the second target spectrum optical device 400
may have a multi-layered structure. In this case, for example, in
some embodiments, the second target spectrum optical device 400 may
have multiple layers of the second nanostructures 404.
In still another example, in some embodiments, as shown in FIGS. 5A
through 5D, the hybrid target spectrum optical device 500 may
include the first nanostructures 304 arranged on the internal
surface of the substrate 502 along a first direction (e.g., an
x-axis direction) and a second direction (e.g., a y-axis direction)
in which the substrate 502 extends, and the second nanostructures
404 arranged on the internal surface of the substrate 502 along the
first direction and the second direction. The first and second
nanostructures 402 and 404 may be spaced apart from each other, and
may each extend in the thickness direction (e.g., the z-axis
direction). The first and second nanostructures 402 and 404 may
have various suitable geometric shapes, sizes, and/or arrangements
to sufficiently focus (e.g., to sufficiently collimate) their
respective target spectrums L1 and L2 on desired spatial locations
(e.g., respective sensing regions of a hybrid thermal sensor). In
some embodiments, the first and second nanostructures 304 and 404
may be spaced apart from each other, and/or may be arranged to not
overlap with each other in the thickness direction (e.g., the
z-axis direction), but the present disclosure is not limited
thereto.
In another example, in some embodiments, as shown in FIG. 5E, the
hybrid target spectrum optical device 500 may include the first
nanostructures 304 arranged on the first surface of the substrate
502, and the second nanostructures 404 arranged on the second
surface of the substrate 502. In this case, the first and second
nanostructures 304 and 404 may extend away from each other in the
thickness direction (e.g., the z-axis direction) of the substrate
502. The first nanostructures 304 may include one or more layers
that are stacked on the first surface of the substrate 502, and the
second nanostructures 404 may include one or more layers that are
stacked on the second surface of the substrate 502. In some
embodiments, the first and second nanostructures 304 and 404 may be
spaced apart from each other, and/or may be arranged to not overlap
with each other in the thickness direction (e.g., the z-axis
direction), but the present disclosure is not limited thereto.
In some embodiments, the first and second nanostructures 304 and
404 may be interleaved with each other in a plan view as shown in
FIG. 5A, such that each of the first and second nanostructures 304
and 404 are arranged across an entirety of the substrate 502 in the
plan view. In this case, a resolution of the hybrid thermal image
detected by the hybrid thermal sensor 206 may be improved, and post
image processing may be reduced. However, the present disclosure is
not limited thereto, and the first and second nanostructures 304
and 404 may be arranged across respective multisector regions of
the substrate 502 in a plan view, for example, in a checker board
shape, a stripe shape, a cross shape, and/or the like, which will
be described in more detail with reference to FIGS. 10A and
10B.
In some embodiments, as shown in FIG. 5B, the first and second
nanostructures 304 and 404 of the hybrid target spectrum optical
device 500 may have a single layer structure. In other words, in
some embodiments, the hybrid target spectrum optical device 500 may
have a single layer structure of the first and second
nanostructures 304 and 404. In this case, in some embodiments, the
first and second nanostructures 304 and 404 may be spaced apart
from each other in the first and second directions (e.g., the
x-axis and y-axis direction) on the substrate 502. In some
embodiments, one or more of the plurality of second nanostructures
404 may be arranged between two adjacent first nanostructures 302
(e.g., in the x-axis direction and/or the y-axis direction), but
the present disclosure is not limited thereto.
In other embodiments, as shown in FIGS. 5C and 5D, the first and
second nanostructures 304 and 404 of the hybrid target spectrum
optical device 500 may have a multi-layered structure. In other
words, in some embodiments, the hybrid target spectrum optical
device 500 may have a multi-layered structure of the first and
second nanostructures 304 and 404. For example, in some
embodiments, the hybrid target spectrum optical device 500 may
include one or more first layers 504 including the first
nanostructures 304, and one or more second layers 506 including the
second nanostructures 404. The one or more first layers 504 and the
one or more second layers 506 may be stacked on each other. For
example, in some embodiments, the one or more first layers 504 may
be alternately stacked with the one or more second layers 506, but
the present disclosure is not limited thereto. While FIGS. 5C and
5D show that a number of the first layers 504 may be the same as a
number of the second layers 506, the present disclosure is not
limited thereto, and the number of the first layers 504 may be
different from that of the second layers 506. In still other
embodiments, as shown in FIG. 5E, the hybrid target spectrum
optical device 500 may include one or more layers of the first
nanostructures 304 on (e.g., stacked on) the first surface of the
substrate 502, and one or more layers of the second nanostructures
404 on (e.g., stacked on) the second surface of the substrate 502
facing away from the first surface.
In some embodiments, when the first and second nanostructures 304
and 404 have the multi-layered structure, the first nanostructures
304 and the second nanostructures 404 may not overlap with each
other in the thickness direction (e.g., the z-axis direction). In
this case, in some embodiments, the first nanostructures 304 of two
different first layers 504 may at least partially overlap with each
other in the thickness direction, and the second nanostructures 404
of two different second layers 506 may at least partially overlap
with each other in the thickness direction. However, the present
disclosure is not limited thereto, for example, in some
embodiments, some of the first nanostructures 304 and some of the
second nanostructures 404 may at least partially overlap with each
other in the thickness direction. In some embodiments, one or more
of the plurality of second nanostructures 404 may be arranged
between two adjacent first nanostructures 302 in a plan view (e.g.,
a view from the z-axis direction), but the present disclosure is
not limited thereto.
In some embodiments, the first nanostructures 304 may have various
suitable geometric shapes and/or sizes (e.g., dimensions) to
sufficiently focus (e.g., to sufficiently collimate) the target IR
spectrum L1 propagating through, and the second nanostructures 404
may have various suitable geometric shapes and/or sizes (e.g.,
dimensions) to sufficiently focus (e.g., to sufficiently collimate)
the other target spectrum L2 propagating through. In some
embodiments, the geometric shape of the first nanostructures 304
may be the same or substantially the same as those of the second
nanostructures 404, or the geometric shape of one or more of the
first nanostructures 304 may be different from those of one or more
of the second nanostructures 404.
In some embodiments, the first nanostructures 304 may have the same
or substantially the same geometric shape as each other, but the
present disclosure is not limited thereto, and at least one of the
first nanostructures 304 may have a different geometric shape from
that of at least one of the others. In some embodiments, at least
some of the first nanostructures 304 may have a different size
(e.g., a different height and/or a different width) from those of
some of the others. In some embodiments, the second nanostructures
404 may have the same or substantially the same geometric shape as
each other, but the present disclosure is not limited thereto, and
at least one of the second nanostructures 404 may have a different
geometric shape from that of at least one of the others. In some
embodiments, at least some of the second nanostructures 404 may
have a different size (e.g., a different height and/or a different
width) from those of some of the others.
For example, in some embodiments, the first nanostructures 304 and
the second nanostructures 404 may each have a cylindrical shape
with various different sizes (e.g., various different widths,
heights, and/or the like), but the present disclosure is not
limited thereto. For example, in other embodiments, the first
nanostructures 304 and the second nanostructures 404 may each have
any suitable geometric shape, for example, such as a square or
rectangular shape, a spherical, ellipsoidal or semi-spherical
shape, a cuboid shape, a cone shape, a prism shape, a pyramid
shape, an irregular shape, and/or the like. In some embodiments,
the first nanostructures 304 may generally have a larger size
(e.g., a larger width or a larger diameter) than those of the
second nanostructures 404, for example, as shown in FIGS. 3 through
5, in order to sufficiently shift a phase of the relevant
wavelengths in the LWIR spectrum, but the present disclosure is not
limited thereto. For example, in order to change a phase of the
longer wavelengths in the LWIR spectrum L1 than those of the other
target spectrum L2, the first nanostructures 304 may generally have
a larger width and/or height than corresponding ones of the
adjacent second nanostructures 304, but the present disclosure is
not limited thereto.
For example, according to some embodiments, the geometric shape
and/or sizes (e.g., widths and/or heights) of the first and second
nanostructures 304 and 404 may depend on a material used to form
the nanostructure and/or corresponding substrate, a target
wavelength of the external light to be focused, a focal length of
the sensor or sensor region (or micro-lens) from the corresponding
optical device, a spatial location of the nanostructure on the
substrate, and/or the like. For example, the geometric shapes
and/or sizes of each of the first and second nanostructures 304 and
404 may depend on a desired shift amount of the phase of the
relevant wavelengths of the respective target spectrums L1 and L2
of the external light propagating through, such that the relevant
wavelengths may be suitably focused (e.g., may be suitably
collimated) on a desired spatial location (e.g., corresponding to
the sensor, the sensor regions, the micro-lenses, and/or the
like).
In some embodiments, the first nanostructures 304 may be made of
the same or substantially the same material as that of the second
nanostructures 404, or may be made of a different material as that
of the second nanostructures 404. As a non-limiting example, in
some embodiments, each of the first and second nanostructures 304
and 404 may be formed of a-Si. As another non-limiting example, in
some embodiments, the first nanostructures 304 may be formed of
a-Si and the second nanostructures 404 may be formed of TiO.sub.2.
In some embodiments, the first nanostructures 304 may have the same
thickness (e.g., the same height in the z-axis direction) as that
of the second nanostructures 404. As a non-limiting example, in
some embodiments, each of the first and second nanostructures 304
and 404 may have a height (e.g., in the z-axis direction) that is
greater than or equal to about 5 .mu.m (e.g., that is greater than
or equal to 5 .mu.m). In other embodiments, the first
nanostructures 304 may have a different thickness (e.g., a
different height in the z-axis direction) as that of the second
nanostructures 404. For example, in some embodiments, each of the
first and second nanostructures 304 and 404 may have a height
(e.g., in the z-axis direction) corresponding to a target
wavelength of light focused by the corresponding nanostructure. As
a non-limiting example, in some embodiments, the first
nanostructures 304 may have a height (e.g., in the z-axis
direction) that is greater than or equal to about 5 .mu.m (e.g.,
that is greater than or equal to 5 .mu.m), and the second
nanostructures 404 may have a height (e.g., in the z-axis
direction) that is less than those of the first nanostructures 304,
for example, such as in a range between about 350 nm to about 750
nm (e.g., in a range between 350 nm and 750 nm). However, the
present disclosure is not limited to the non-limiting examples
provided herein.
In some embodiments, when the first and second nanostructures 304
and 404 are formed to have the single-layer structure, for example,
as shown in FIG. 5B, it may be difficult to form the first
nanostructures 304 from a different material from that of the
second nanostructures 404, and/or to form the first nanostructures
404 to have a different thickness (e.g., a different height in the
z-axis direction) from that of the second nanostructures 404.
Accordingly, in some embodiments, the multi-layer structure of the
first and second nanostructures 304 and 404, for example, as shown
in FIGS. 5C through 5E, may enable the first nanostructures 304 to
be formed from a different material from that of the second
nanostructures 404, and/or to be formed to have different heights
(e.g., different thicknesses in the z-axis direction) from that of
the second nanostructures 404. However, the present disclosure is
not limited thereto, and in some embodiments, the first and second
nanostructures 304 and 404 of the single-layer structure (e.g., see
FIG. 5B) may be formed from different materials and/or to have
different heights from each other.
FIG. 6 is a table showing a list of example suitable materials for
a substrate of the optical device according to one or more example
embodiments of the present disclosure, and FIG. 7 is a table
showing a list of example suitable materials for a nanostructure of
the optical device according to one or more example embodiments of
the present disclosure. FIGS. 8A and 8B are graphs illustrating a
relationship between the transmission and phase of light and a
diameter of a nanostructure of the optical device according to one
or more example embodiments of the present disclosure.
Referring to FIG. 6, a suitable transparent material for the
substrate may sufficiently transmit the relevant wavelengths of the
target spectrum (e.g., L1 and/or L2) of the external light through.
For example, in some embodiments, the substrate of the optical
device according to one or more example embodiments of the present
disclosure may include calcium fluoride CaF2, but the present
disclosure is not limited thereto. Referring to FIG. 7, a suitable
material for the nanostructures may sufficiently transmit the
relevant wavelengths of the target spectrum (L1 and/or L2) of the
external light through. For example, in some embodiments, the
nanostructures of the optical device according to one or more
example embodiments of the present disclosure may include amorphous
silicon (a-Si) or other suitable dielectric material, for example,
such as c-Si, p-Si, Ge, GaAs, ZnS, ZnSe, Si.sub.3N.sub.4,
TiO.sub.2, HfO.sub.2, and/or the like, but the present disclosure
is not limited thereto. In some embodiments, the first
nanostructures 304 and the second nanostructures 404 may include
the same material (e.g., a-Si) as each other. In other embodiments,
the first nanostructures 304 may include a different material from
that of the second nanostructures 404. For example, in some
embodiments, the first nanostructures 304 may be formed of, for
example, a-Si, and the second nanostructures 404 may be formed of,
for example, TiO.sub.2, but the present disclosure is not limited
thereto.
Referring to FIG. 8A, the graph illustrates a relationship between
the transmission 802 and phase 804 of light for various different
widths (e.g., diameters) of a nanostructure including amorphous
silicon (a-Si). The graph of FIG. 8A assumes that the substrate
includes potassium bromide (KBr), and the nanostructure has a
cylindrical shape with a height (e.g., in the z-axis direction) of
about 4 .mu.m. A square lattice having a lattice constant (e.g.,
pixel size) of about 5 .mu.m and a light having a target wavelength
of 10 .mu.m was used to simulate the graph of FIG. 8A.
As shown in FIG. 8A, a 2.pi. phase shift of the target wavelength
of light may be generated as the diameter (e.g., as represented by
the X-axis) of the nanostructure is increased. For example, FIG. 8A
illustrates that transmission 802 is greater than about 95% in 80%
of 2.pi. phases 804 achieved, which may be suitable for low
numerical apertures (NA) applications, and that transmission 802 is
greater than about 70% in all phases 804 achieved, which may be
suitable for high NA applications. However, transmission 802
through the nanostructure may be unsuitably decreased when the
diameter of the nanostructure is too large. Thus, according to one
or more example embodiments of the present disclosure, the diameter
of the nanostructure may be selected according to a desired
transmission 802 and phase 804 shown in the graph of FIG. 8A, but
the diameters corresponding to a non-applicable area NA of the
graph may be avoided to prevent or substantially prevent low
transmission.
Referring to FIG. 8B, the graph illustrates a relationship between
the transmission 802 and phase 804 of light for various different
widths (e.g., diameters) of a nanostructure including amorphous
silicon (a-Si). The graph of FIG. 8B assumes that the substrate
includes calcium fluoride (CaF2), and the nanostructure has a
cylindrical shape with a height (e.g., in the z-axis direction) of
about 5 .mu.m. A square lattice having a lattice constant of about
5 .mu.m and a light having a target wavelength of 10 .mu.m was used
to simulate the graph of FIG. 8B.
As shown in FIG. 8B, a 2.pi. phase shift of the target wavelength
of light may be generated as the diameter (e.g., as represented by
the X-axis) of the nanostructure is increased within an applicable
area AA of the graph. However, transmission 802 through the
nanostructure may be unsuitably decreased when the diameter of the
nanostructure is too large. Thus, according to one or more example
embodiments of the present disclosure, the diameter of the
nanostructure may be selected according to a desired transmission
802 and phase 804 shown in the graph of FIG. 8B, but larger
diameters of the nanostructure outside of the applicable area AA of
the graph may be avoided to prevent or substantially prevent low
transmission. For example, in some embodiments, the nanostructures
for transmitting and focusing the IR target spectrum L1 may have
different widths in a range between about 1 .mu.m and 3.1 .mu.m,
but the present disclosure is not limited thereto.
In some embodiments, the height of the nanostructures may vary in
order to vary the performance, but may be challenging to fabricate
as discussed above. For example, in some embodiments, the first
nanostructures 304 may have a thickness (e.g., in the z-axis
direction) of at least 5 .mu.m for a complete 2.pi. phase shift
with high transmission of a 10 .mu.m wavelength of the IR target
spectrum L1, whereas when the second nanostructures 404 have the
thickness of 5 .mu.m, the second nanostructures 404 may exhibit
multiple cycles of 2.pi. phase shifts with variable transmission of
a 600 nm wavelength of the other target spectrum L2. Accordingly,
in some embodiments, the first nanostructures 304 and the second
nanostructures 404 may be formed at different layers from each
other (e.g., see FIGS. 5C-5E), such that the material and/or the
height of the first and second nanostructures 304 and 404 may be
variously formed.
FIGS. 10A and 10B illustrate a hybrid target spectrum optical
device according to one or more example embodiments of the present
disclosure. For example, FIG. 10A shows a plan view and FIG. 10B
shows a perspective view of the hybrid target spectrum optical
device 1000. The hybrid target spectrum optical device 1000 of FIG.
10 may be the same or substantially the same as the hybrid target
spectrum optical device 500 of FIG. 5, except for an arrangement of
the first and second nanostructures 304 and 404, and thus,
redundant description thereof may not be repeated or may be
simplified. While FIG. 10B shows that the first and second
nanostructures 304 and 404 are arranged on opposite surfaces of the
substrate 502, the present disclosure is not limited thereto, and
the first and second nanostructures 304 and 404 may be arranged as
a single layer (e.g., see FIG. 5B), or as multiple layers that are
stacked on one another (e.g., see FIGS. 5C and 5D).
Referring to FIGS. 10A and 10B, in some embodiments, each of the
first and second nanostructures 304 and 404 may be arranged at
respective multisector regions on the substrate 502. For example,
the first nanostructures 304 may be arranged across a first
multisector region 1002, and the second nanostructures 404 may be
arranged across a second multisector region 1004. In this case, the
first and second multisector regions 1002 and 1004 may not overlap
with each other in a plan view, and thus, a plurality of the first
nanostructures 304 of the first multisector region 1002 may not
overlap with a plurality of second nanostructures 404 of the second
multisector region 1004 in a plan view. For example, rather than
the first and second nanostructures 304 and 404 being interleaved
with each other across an entirety of the substrate 502, the first
and second nanostructures 304 and 404 may be arranged only at their
respective first and second multisector regions 1002 and 1004.
In some embodiments, the first nanostructures 304 arranged at the
first multisector region 1002 and the second nanostructures 404
arranged at the second multisector region 1004 may be formed of
different materials from each other. For a non-limiting example, in
some embodiments, the first nanostructures 304 arranged at the
first multisector region 1002 may be formed of a-Si, and the second
nanostructures 404 arranged at the second multisector region 1004
may be formed of TiO.sub.2. In this case, the first nanostructures
304 may have a different width and/or a different height from that
of the second nanostructures 404. For example, in some embodiments,
the first nanostructures 304 may have a height (e.g., in the z-axis
direction) that is greater than or equal to about 5 .mu.m, and the
second nanostructures 404 may have a height (e.g., in the z-axis
direction) that is between about 200 nm and about 700 nm. For
example, in some embodiments, the first nanostructures 304 may have
a width (e.g., in the x-axis or y-axis direction) that is less than
or equal to about 3 .mu.m and the second nanostructures 404 may
have a width (e.g., in the x-axis or y-axis direction) that is less
than or equal to about 350 nm. In some embodiments, increasing the
height (e.g., in the z-axis direction) of the first nanostructures
304 may improve performance. For example, in some embodiments,
increasing the height of the first nanostructures 304 from 5 .mu.m
to 6 .mu.m may increase transmission from about 41% to about 49%,
and may increase a field effect from about 34% to about 44%.
While FIGS. 10A and 10B show that each of the first and second
multisector regions 1002 and 1004 have a cross shape in a plan
view, the present disclosure is not limited thereto, and the first
and second regions 1002 and 1004 may have any suitable shape, for
example, such as a stripe shape, a checker board shape, and/or the
like. In the case of the checker board shape, each of the first
multisector regions 1002 of the checker board shape may include a
plurality of the first nanostructures 204, each of the second
multisector regions 1004 of the checker board shape may include a
plurality of the second nanostructures 204, and the plurality of
the first and second nanostructures 304 and 404 of each of the
first and second regions 1002 and 1004 may not overlap with each
other. In some embodiments, depending on a shape or an arrangement
of the first and second multisector regions 1002 and 1004, a
resolution of the hybrid thermal image may be improved. For
example, in some embodiments, the checker board shape may be
arranged to have better coverage than that of the cross shape shown
in FIGS. 10A and 10B, and thus, may have a 30% improvement in
resolution.
In the drawings, the relative sizes of elements, layers, and
regions may be exaggerated and/or simplified for clarity. Spatially
relative terms, such as "beneath," "below," "lower," "under,"
"above," "upper," and the like, may be used herein for ease of
explanation to describe one element or feature's relationship to
another element(s) or feature(s) as illustrated in the figures. It
will be understood that the spatially relative terms are intended
to encompass different orientations of the device in use or in
operation, in addition to the orientation depicted in the figures.
For example, if the device in the figures is turned over, elements
described as "below" or "beneath" or "under" other elements or
features would then be oriented "above" the other elements or
features. Thus, the example terms "below" and "under" can encompass
both an orientation of above and below. The device may be otherwise
oriented (e.g., rotated 90 degrees or at other orientations) and
the spatially relative descriptors used herein should be
interpreted accordingly.
It will be understood that, although the terms "first," "second,"
"third," etc., may be used herein to describe various elements,
components, regions, layers and/or sections, these elements,
components, regions, layers and/or sections should not be limited
by these terms. These terms are used to distinguish one element,
component, region, layer or section from another element,
component, region, layer or section. Thus, a first element,
component, region, layer or section described below could be termed
a second element, component, region, layer or section, without
departing from the spirit and scope of the present disclosure.
It will be understood that when an element or layer is referred to
as being "on," "connected to," or "coupled to" another element or
layer, it can be directly on, connected to, or coupled to the other
element or layer, or one or more intervening elements or layers may
be present. In addition, it will also be understood that when an
element or layer is referred to as being "between" two elements or
layers, it can be the only element or layer between the two
elements or layers, or one or more intervening elements or layers
may also be present.
The terminology used herein is for the purpose of describing
particular embodiments and is not intended to be limiting of the
present disclosure. As used herein, the singular forms "a" and "an"
are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises," "comprising," "includes," and
"including," "has," "have," and "having," when used in this
specification, specify the presence of the stated features,
integers, steps, operations, elements, and/or components, but do
not preclude the presence or addition of one or more other
features, integers, steps, operations, elements, components, and/or
groups thereof. As used herein, the term "and/or" includes any and
all combinations of one or more of the associated listed items.
Expressions such as "at least one of," when preceding a list of
elements, modify the entire list of elements and do not modify the
individual elements of the list.
As used herein, the term "substantially," "about," and similar
terms are used as terms of approximation and not as terms of
degree, and are intended to account for the inherent variations in
measured or calculated values that would be recognized by those of
ordinary skill in the art. Further, the use of "may" when
describing embodiments of the present disclosure refers to "one or
more embodiments of the present disclosure." As used herein, the
terms "use," "using," and "used" may be considered synonymous with
the terms "utilize," "utilizing," and "utilized," respectively.
Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which the present
disclosure belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and/or the present
specification, and should not be interpreted in an idealized or
overly formal sense, unless expressly so defined herein.
Although some example embodiments have been described, those
skilled in the art will readily appreciate that various
modifications are possible in the example embodiments without
departing from the spirit and scope of the present disclosure. It
will be understood that descriptions of features or aspects within
each embodiment should typically be considered as available for
other similar features or aspects in other embodiments, unless
otherwise described. Therefore, it is to be understood that the
foregoing is illustrative of various example embodiments and is not
to be construed as limited to the specific example embodiments
disclosed herein, and that various modifications to the disclosed
example embodiments, as well as other example embodiments, are
intended to be included within the spirit and scope of the present
disclosure as defined in the appended claims, and their
equivalents.
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